Folding rule



' J.. H. MCCAFFREY FOLDING RULE Filed Dec. 21. 1942s Patented July 15,1924.

UNITED STATES PATENT OFFICE.

JAMES E. MCCAFFREY, OF BUFFALO, NEW YORK.

FOLDING RULE.

Application filed December 21, 1923. Serial No. 681,949.

This invention relates to the class of folding or extension rules inwhich the sections are foldable laterally or edgewise upon one anotherand provided with resilient means for automatically locking them both intheir folded and unfolded positions.

The object of the invention is the improvement of the lock joints of therule-sections with a view of rendering them neat, compact, firm andreliable, while at the same time permitting the sections to be easilyunlocked or turned from one position to an; other.

In the accompanying drawings:

Figure 1 is a perspective view of an eX- tension rule embodying theinvention. Figure 2 is an enlarged longitudinal section of one of thejoints, showing the rule-sections fully unfolded. Figure 3 is a similarsection, showing the rule-sections, partly unfolded to correspond to theposition illustrated by dotted lines in Fig. 1. Figures 4 and 5 arecross sections on the correspondingly numbered lines in Fig. 2. Figure 6is an edge view of one of the rule-sections. Figures 7 and 8 areperspective views of the j oint-plates, respectively.

Similar characters of reference indicate corresponding parts in theseveral views.

10 and 11 indicate adjoining sections of the rule which are graduated asusual and pivotally united by a transverse rivet 12. Between the pivotedoverlapping end portions of the sections are interposed a pair ofjoint-plates 13 and 14, which are secured to the respective sections byany suitable means and stamped of a suitable resilient material, such ashard spring brass. In the preferred construction shown, each plate isprovided at its side edges with flanges 15 which embrace the bevelededges of the companion rule-section which is recessed to receive theflanges and form a flush joint.`

Each joint plate has a central opening 16 for the passage of the rivetor pivot 12, and one of the plates is provided on opposite sides of saidopening with a pair of studs or teats 17 arranged to interlock with acorre sponding pair of holes or sockets 18 in the other plate, when thesections are turned on each other to their fully folded or unfoldedposition. For this purpose, the complemental locking'studs and openingsare arranged in a line extending centrally and lengthwise of the platesand are located equidistant from the pivot 12. As shown in Fig. 6, the

joint plates and the corresponding end porv tions of the rule-sectionsare preferably arched lengthwise, so that when the rule is fully foldedor unfolded, the plates are practically flattened out, placing themunder tension and offering frictional resistance to the folding andunfolding movements of the rule-sections. If desired, the plates mayalso be arched crosswise to a slight degree.

Surrounding the pivot-hole of each plate is a hollow, comparativelyshallow boss `or dished portion 19, preferably of circular 1 form.; Theopposing bosses face each other with their concave sides and` formsprings which supplement the action of the arched joint plates, allowingthe locking studs to snap into and rise out of the locking openings, infolding and unfolding the rule sec# tions. When the studs leave theopenings and ride up on the face of the opposing plate, the bosses 19are deflected or drawn toward each other, as shown in Fig. 3, the degreeof their deflection being exaggerated for the sake of clearness. Thebosses spring back to their normal position the moment the sections comeinto alinement and the studs snap into the openings, as illustrated inFig. 2.

As shown, the headed ends of the pivot pass loosely through openings 20of the rule sections and the head at one end of the pivot and the washer12a at the other end bear directly against the backs of the bosses 19,respectively.

To facilitate the locking action of the rulesections, the bearing faces17a of the studs are preferably inclined toward the pivot 12, as shownin Figs. 2 and 3.

While producing a strong, firm and reliable locking-joint thisconstruction permits the joints to be easily broken7 or unlocked infolding and unfolding the rule. This construction also affords thefurther advantages of lightness, neatness and compactness, and enablesthe joint plates to be made comparatively short without sacrificingstiffness and firmness of the rule-sections when unfolded. This rendersthe improvement especially desirable for small or vest-pocket rules.

lloreover, the spring-bosses tend to take up Wear of the locking studsand openings, I

and permit the joint plates to be arched to a less degree than Withoutthem, relieving the plates and the connecting rivet from undue strain.

The arching of the pla-tes, combined with the spring bosses, also tendsto hold the adjoining rule-sections closely together at both ends, Whenfolded, reducing the folded rule to the smallest compass.

l claim as my invention:

l. The combination of a pair of adjoining rule-sections, joint-platessecured to the respectire sections and having' opposing; dished portionsforming` springs, the concave sides of sain dished portions facing eachother, and a pivot connecting; said plates and passing; through saiddished portions, the plates being provided with complementallockingdevices arranged to interlock in the folded and unfoldedpositions of the sections.

2. The combination of a pair of adjoining rulesections, joint-platessecured to the respective sect-ions and having1 opposing hollow bossesWhose concave sides tace each other, and a pivot connecting' said platesand passing centrally through said bosses, the plates being` provided inaddition` to said bosses With oomplemental looking devices.

3. The combination of a pair of adjoining rule-sections, joint-platessecured to the respective sections and a pivot connecting said plates,the latter havingr complemental locking teats and openings located onoppositeV sides of said pivot, and each plate having a hollow integralboss surrounding said pivot and forminga spring, the concave sides ofsaid bosses facing each other.

4. The combination of a'pair of adjoining` 2.

rule-sections, arched joint plates secured to the respective sectionsand having opposing (lished portions forming springs, the concave sidesof said dished portions facing each other, and a pivot connecting saidt;

plate having a hollow integral boss surrounding` said pivot and forminga spring, the concave sides ot said bosses facing' each other.

JAMES MCCAFFREY.

The combination of a pair ot' adjoining.

